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block: return whether or not to unplug through boolean

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Instead of returning the same queue request through a request pointer,
use a boolean to accomplish the same.

Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Jens Axboe 2021-10-18 10:07:09 -06:00
parent 8a7d267b4a
commit 87c037d11b
3 changed files with 15 additions and 14 deletions
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11
block/blk-merge.c
View File

@ -1067,9 +1067,8 @@ static enum bio_merge_status blk_attempt_bio_merge(struct request_queue *q,
* @q: request_queue new bio is being queued at
* @bio: new bio being queued
* @nr_segs: number of segments in @bio
* @same_queue_rq: pointer to &struct request that gets filled in when
* another request associated with @q is found on the plug list
* (optional, may be %NULL)
* @same_queue_rq: output value, will be true if there's an existing request
* from the passed in @q already in the plug list
*
* Determine whether @bio being queued on @q can be merged with the previous
* request on %current's plugged list. Returns %true if merge was successful,
@ -1085,7 +1084,7 @@ static enum bio_merge_status blk_attempt_bio_merge(struct request_queue *q,
* Caller must ensure !blk_queue_nomerges(q) beforehand.
*/
bool blk_attempt_plug_merge(struct request_queue *q, struct bio *bio,
unsigned int nr_segs, struct request **same_queue_rq)
unsigned int nr_segs, bool *same_queue_rq)
{
struct blk_plug *plug;
struct request *rq;
@ -1096,12 +1095,12 @@ bool blk_attempt_plug_merge(struct request_queue *q, struct bio *bio,
/* check the previously added entry for a quick merge attempt */
rq = list_last_entry(&plug->mq_list, struct request, queuelist);
if (rq->q == q && same_queue_rq) {
if (rq->q == q) {
/*
* Only blk-mq multiple hardware queues case checks the rq in
* the same queue, there should be only one such rq in a queue
*/
*same_queue_rq = rq;
*same_queue_rq = true;
}
if (blk_attempt_bio_merge(q, rq, bio, nr_segs, false) == BIO_MERGE_OK)
return true;

16
block/blk-mq.c
View File

@ -2432,7 +2432,7 @@ void blk_mq_submit_bio(struct bio *bio)
const int is_flush_fua = op_is_flush(bio->bi_opf);
struct request *rq;
struct blk_plug *plug;
struct request *same_queue_rq = NULL;
bool same_queue_rq = false;
unsigned int nr_segs = 1;
blk_status_t ret;
@ -2525,6 +2525,8 @@ void blk_mq_submit_bio(struct bio *bio)
/* Insert the request at the IO scheduler queue */
blk_mq_sched_insert_request(rq, false, true, true);
} else if (plug && !blk_queue_nomerges(q)) {
struct request *next_rq = NULL;
/*
* We do limited plugging. If the bio can be merged, do that.
* Otherwise the existing request in the plug list will be
@ -2532,19 +2534,19 @@ void blk_mq_submit_bio(struct bio *bio)
* The plug list might get flushed before this. If that happens,
* the plug list is empty, and same_queue_rq is invalid.
*/
if (list_empty(&plug->mq_list))
same_queue_rq = NULL;
if (same_queue_rq) {
list_del_init(&same_queue_rq->queuelist);
next_rq = list_last_entry(&plug->mq_list,
struct request,
queuelist);
list_del_init(&next_rq->queuelist);
plug->rq_count--;
}
blk_add_rq_to_plug(plug, rq);
trace_block_plug(q);
if (same_queue_rq) {
if (next_rq) {
trace_block_unplug(q, 1, true);
blk_mq_try_issue_directly(same_queue_rq->mq_hctx,
same_queue_rq);
blk_mq_try_issue_directly(next_rq->mq_hctx, next_rq);
}
} else if ((q->nr_hw_queues > 1 && is_sync) ||
!rq->mq_hctx->dispatch_busy) {

2
block/blk.h
View File

@ -218,7 +218,7 @@ void blk_add_timer(struct request *req);
void blk_print_req_error(struct request *req, blk_status_t status);
bool blk_attempt_plug_merge(struct request_queue *q, struct bio *bio,
unsigned int nr_segs, struct request **same_queue_rq);
unsigned int nr_segs, bool *same_queue_rq);
bool blk_bio_list_merge(struct request_queue *q, struct list_head *list,
struct bio *bio, unsigned int nr_segs);